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Complete Guide to Fixing 850 AC/Evap/Heater Controls

Fixing the AC: Just in time for hot summer months (in the Northern Hemisphere), MVS forums member Fish Sticks drops a wonderful writeup and list on how to fix 850 AC/Heater Controls/AC Evaporator.

Volvo 850 AC, Heater, Climate Control fix

  • Climate unit sketch
  • Specifications for the AC, and Heating system
  • Dash Sketch
  • Damper Box, assembly Sketch
  • How to remove the problematic Damper control arm
  • Floor Shutter Fix
  • Better look on the removal of the floor dampers, If youre having this problem.
  • Entire dash removal link

“Like I said sorry for the overload, but i prepared about 3-4 months for this, and it went rather well for me. The more reading, and specific understanding of this area of your car, the better.

Also, i didn’t mention, but “felt tape” is quite nice to have as well, because you will need to put stuff back in, this helps to reduce noise, and sound (especially Squeaks).”

Climate Control, Evap., fixes w/ parts list

What brand of evaporator?

OEM Volvo or Behr (which is OEM)

Do heater core if no problems currently exist??

It would be a good idea if it’s more than 10 years old!

What about air flap seals and controls?

If they work, don’t worry about it

How do correctly identify the or rings I need for the A/C core, accumulator etc?

You need four O rings, two for the Evap and two for the heater core, that’s it!

What brand Accumulator?

Whatever you want, they all work

Are there known or expected pitfalls? Something that frequently/always breaks that i should have a part ready for?

Just be REAL with fixing the AC; careful with the cheap plastic dash clips, poor design, not strong and if you break those and you’re totally fracked!


Post by rspi » Wed Jul 04, 2012 5:36 am

LOL, I’d like to start off by saying, if it’s not loosing the coolant at a rate of a can per 2 months, leave it. It’s just not worth the work. They claim that R134 or whatever it is, is not harmful to the ozone so $8 per 2 months is nothing compared to the cost and work you are about to face.

I used Nissens and all went smooth except I always try to put the flapper door plastic piece on backwards and break it, every time. I keep forgetting that it swivels and spins around. The part will come WITHOUT the “O” rings that I got from Volvo. When you get them from Volvo, make sure they give you the Evaporator “O” rings because they are so conditioned on giving out the heater core “O” rings that they may just do it again. Caused me a head ache.

There is a good write-up here on VolvoForums. I keep meaning to add photo’s to it but keep forgetting. I used the pics from Kodac but you say they’re gone, not sure why. … ions-1696/

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